If you've kept mbuna, haps will be no problem. The main differences: diet- haps are generally piscavores which can be fed any carnivorous diet, decor - they prefer minimal decor as they are mostly open water predators, size - they can range from 3" to over 18". Just like mbuna you do need to stock very carefully.
Dimidiochromis compressiceps isn't going to work for your tank, at 11" and very active and aggressive, they need a minimum 6ft tank.
<a href="http
/www.cichlid-forum.com/articles/d_compressiceps.php" target="_blank">http
/www.cichlid-forum.com/articles/d_compressiceps.php</a>
There are quite a few other haps that would work in it though, what else are you interested in?